Z axis calibration help

After some prints and test i have found out that the Z-axis is no more synchronize. That is not a surprise because we have two stepper Motors for the Z-axis and after some time they are no more synchronize. For that reason I misplaced the Hotbet. After some settings with the caliper and folding rule I was dissatisfied and make this small helping Thing. You need only a folding rule and dissected it.

I have dissected the folding rule at 10,5 cm (you can let it be longer if you want) and insert